The instant invention pertains to concentrates which comprise a biocidal compound and a polyester carrier resin. The addition of such concentrates into polymer substrates provides biocidal activity to said polymer substrate while preventing discoloration of the substrate.
WO 92/07031 teaches the process for preparing a soluble-stable dispersion of a solid biocide comprising a swellable vinyl polymer with a liquid carrier to enable the incorporation of difficultly soluble biocides into polymer resins.
British Patent No. 2,262,468 describes the application of a composition comprising a biocide in a poly(vinyl alcohol) carrier medium to the surface of a mold or former in order to render a plastic article biocidally active during the manufacturing process.
Japanese Sho 62-000544 teaches the incorporation of an antibiotic by premixing it with poly(ethylene glycol) or silicone oil and melt blending the pre-mixture into a polyester resin or by preparing a master batch containing the antibiotic in a higher concentration and melting blending the master batch into the polyester.
While the process for putting biocides into plastics by adding the neat active biocidal compound into the polymer substrate during processing or manufacturing is known, this process can lead to discoloration of the final biocidally active substrate. The instant process involves preparing first a biocide-polyester concentrate which is then subsequently added to the polymer substrate. This leads to a final product which is both biocidally active and is resistant to discoloration.
One object of this invention provides for biocide-polyester concentrates useful for later incorporation into polymer substrates.
Another object of this invention provides for biocidally active polymer compositions resistant to discoloration made by the incorporation of said biocide-polyester concentrate into the polymer.
The instant invention pertains to a biocide-polyester concentrate which comprises
(A) 1-75% by weight of a biocide, and
(B) 99-25% by weight of a polyester carrier resin.
Preferably, component (A) is 10-50% by weight of a biocide, and component (B) is 90-50% by weight of a polyester carrier resin.
The biocide (A) is at least one compound selected from the group consisting of (a) halogenated organic compounds, such as 2,4,4xe2x80x2-trichloro-2xe2x80x2-hydroxydiphenyl ether (IRGASAN(copyright) or IRGAGUARD(copyright), Ciba Specialty Chemicals Corp.);
(b) organosulfur compounds, such as methylene-dithiocyanate, 2-N-octyl-4-isothiazolin-3-one, 3,5-dimethyl-tetrahydro-1,3,5-2H-thiodiazine-2-thione;
(c) s-triazine compounds, such as 2-methylthio-4-tert-butylamino-6-cyclopropyl-amino-s-triazine;
(d) copper or copper compounds, such as copper sulfate, copper nitrate, copper-bis(8-hydroxyquinoline);
(e) organotin compounds, such as tributyltin oxide and its derivatives; and
(f) bactericides, such as silver and zinc compounds, oxy-bis-phenoxyarsine.
The polyester carrier resin (B) is a homopolyester or a copolyester prepared from aliphatic, cycloaliphatic or aromatic dicarboxylic acids and diols or hydroxycarboxylic acids.
Preferably, the polyester of component (B) has dicarboxylic acid repeat units selected from the group consisting of aromatic dicarboxylic acids having 8 to 14 carbon atoms, aliphatic dicarboxylic acids having 2 to 40 carbon atoms, cycloaliphatic dicarboxylic acids having 6 to 10 carbon atoms, aliphatic hydroxycarboxylic acids having 2 to 12 carbon atoms, aromatic and cycloaliphatic hydroxycarboxylic acids having 7 to 14 carbon atoms, and mixtures thereof.
Preferably such aromatic diacids are terephthalic acid, isophthalic acid, o-phthalic acid, 1,3-, 1,4-, 2,6- and 2,7-naphthalenedicarboxylic acid, 4,4xe2x80x2-biphenyldicarboxylic acid, di(4-carboxyphenyl) sulfone, 4,4xe2x80x2-benzophenonedicarboxylic acid, 1,1,3-trimethyl-5-carboxy-3-(p-carboxyphenyl)indane, di(4-carboxyphenyl) ether, bis(p-carboxy-phenyl)methane and bis(p-carboxyphenyl)ethane.
Most preferably, the aromatic diacids are terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid.
Suitable aliphatic dicarboxylic acids are linear or branched. Preferably such aliphatic dicarboxylic acids are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, trimethyladipic acid, sebacic acid, azelaic acid and dimeric acids (products of the dimerization of unsaturated, aliphatic acids such as oleic acid), alkylated malonic acid, alkylated succinic acid, and mixtures thereof.
Suitable cycloaliphatic dicarboxylic acids are 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and 1,4-(dicarboxymethyl)cyclohexane and 4,4xe2x80x2-dicyclohexyldicarboxylic acid.
The diol or glycol portion of the polyester of component (a) are derived from the generic formula HO-R-OH where R is an aliphatic, cycloaliphatic or aromatic moiety of 2 to 18 carbon atoms.
Preferably such diols or glycols are ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propane-diol, 1,2-, 1,3-, 2,3- and 1,4-butane-diol, pentane-1,5-diol, neopentane glycol, hexane-1,6-diol, dodecane-1,12-diol, 1,4-cyclohexanedimethanol, 3-methylpentane-2,4-diol, 2-methylpentanel, 4-diol, 2,2-diethylpropane-1,3-diol, 1,4-di-(hydroxyethoxy)benzene, 2,2-bis(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)propane, 2,2-bis-(4-hydroxypropoxyphenyl)ethane, 1,4dihydroxycyclohexane, p-xylylene glycol, poly(ethylene glycol), poly(propylene glycol), and mixtures thereof.
Preferably, the diol is 1,4-dihydroxycyclohexane, 1,4-cyclohexanedimethanol, ethylene glycol, 1,4-butanediol, 1,2-propylene glycol and 1,3-trimethylene glycol.
Most preferably, the diol is ethylene glycol.
It is furthermore possible for the polyester to be branched by small amounts, for example 0.1 to 3 mol %, based on the dicarboxylic acid present, of monomers having a functionality greater than two, e.g. pentaerythritol, trimellitic acid, 1,3,5-tri(hydroxyphenyl)benzene, 2,4dihydroxybenzoic acid or 2-(4-hydroxyphenyl-2-(2,4-dihydroxyphenyl)propane.
In the polyester comprising at least two monomers, the polymer can have randomly distributed units or units arranged in the form of blocks.
The polyester of component (B) is preferably poly(ethylene terephthalate) PET, poly(ethylene 2,6-naphthalene-2,6dicarboxyiate) PEN or poly(ethylene/1,4-cyclo-hexylenedimethylene terephthalate) PETG copolyester, EASTAR(copyright) 6763, Eastman Chemical); most preferably, poly(ethylene terephthalate) or the poly(ethylene/1,4-cyclo-hexylenedimethylene terephthalate) copolyester.
It is also contemplated that the polyester of component (B) can also be a blend of polyesters or copolyesters including components mentioned above.
The instant invention also pertains to biocidally active polymer compositions resistant to discoloration which comprise
(I) a polymer substrate, and
(II) an effective biocidal amount of a concentrate described above.
The effective biocidal amount of the active component is 0.01 to 5% by weight based on the total composition.
The instant invention also relates to a process for preparing a biocidally active polymer composition, which is resistant to discoloration, which comprises
incorporating into said polymer an effective biocidal amount of a concentrate described above.
The polymer substrate of component (I) is a polyolefin, polystyrene, polyamide, polycarbonate, a polystyrenic such as ABS, SAN, ASA, a nylon (a polyamide), a polyurethane, an acrylate, a polyacrylonitrile a rubber modified styrenic, poly(vinyl chloride), poly(vinyl butyral) or a polyacetal (polyoxymethylene).
Preferably, the polymer substrate is a polyolefin or a polystyrenic, especially polypropylene or polyethylene, most especially linear low density polyethylene (LLDPE), low density polyethylene (LDPE) and high density polyethylene (HDPE).
The incorporation of the instant biocide-polyester concentrate into the polymer substrate affords a number of real advantages over using a neat biocide for the same purpose.
These advantages are
a. better handling;
b. improved industrial hygiene and environmental concerns; and
c. improved control of dosing accuracy for insertion of biocide into the polymer substrate.
Most of all and surprising is the advantage that the use of the biocide-polyester concentrate, when added to a variety of polymer substrates, leads to resistance to discoloration in the biocidally active polymer substrate as compared to the incorporation of neat biocide directly into the polymer substrate.